The code designation of the concentrator is RT:C (R--refracting section of a stage lens, T--transmitting section of a stage lens, and C--concentrating stage lens).
Prior art includes the Conical Refractor, U.S. Pat. No. 2,882,784, 4/21/84, by D. S. Toffolo. This lens is similar in shape, but it is designed to receive an annular beam and emit a concentrated circular whole beam. It cannot produce a concentrated circular whole beam from a convergent conical beam because its convex and concave sections are parallel.